1. Field of the Invention
The present invention relates to an image forming apparatus capable of changing the execution order of jobs, a method of controlling the image forming apparatus, and a storage medium.
2. Description of the Related Art
In a printing market, which is called the print-on-demand (POD) market or the production market, a form of business is adopted in which printing is performed according to an order placed by a customer and then a print product is reliably delivered to the customer on or before desired delivery date.
In a job site in the printing market, it is very important to perform large-amount printing speedily. For this reason, in many cases, an operator who performs various operations on a printing apparatus as a specialist is assigned to the job site.
The operator as a specialist performs replenishment/replacement of consumables, such as sheets and toner, job management, job ticket editing, conveyance of printed sheets, and post processing of printed sheets, such as cutting and bookbinding.
Replenishment/replacement of consumables is a most important task among operator operations, because when replenishment/replacement of consumables is not properly performed, the printing apparatus is brought into a state where a consumable necessary for printing runs out during execution of a print job.
In such a case, the printing apparatus has to temporarily stop its print engine to suspend a printing process. When the printing process is suspended, printing cannot be restarted until replenishment/replacement of consumables necessary for printing is completed. Further, reheating of the print engine and the like processing are executed after restart of the printing, and hence long downtime occurs before the printing apparatus becomes capable of executing printing again.
Therefore, as a method of enabling the operator to take necessary steps before occurrence of downtime, there has been disclosed a technique in which, in a graph indicating predicted printing times on a job-by-job basis, a portion indicating a time period during which downtime is predicted to occur is displayed using a different color (see e.g. Japanese Patent Laid-Open Publication No. 2004-330781).
According to the above-described conventional technique, however, although the operator can grasp in advance when it becomes necessary to perform an operation for replenishing/replacing consumables, there can be a case where the operator has to leave the printing site at a time during which it becomes necessary to perform the operation, due to another activity or a meeting or for some other reason.
In this case, although it is possible to shift timing of occurrence of downtime by replenishing/replacing sufficient consumables before the operator leaves the printing site, it is not always possible to replenish/replace sufficient consumables before the operator leaves the printing site.
For example, in cases where it takes time to acquire a necessary consumable, where the number of sheets necessary for printing is larger than the number of sheets which can be contained in a sheet feeder, and where the number of necessary sheet types is larger than the number of sheet feeders, it is impossible to replenish or replace the consumable instantly, and hence it is supposed that the operator leaves the printing site without replenishing or replacing the consumable.
Even in such a case, as another method of shifting timing of occurrence of downtime, if the operator changes the execution order of jobs, it is sometimes possible to prevent a consumable from running out when the operator is absent from the printing site. That is, by changing the printing order of jobs such that jobs which will consume the consumable predicted to run short are advanced or delayed, the consumable is prevented from running out when the operator is absent from the printing site.
However, it costs the operator much time and labor for manually changing the execution order of jobs, because the operator is required to change the execution order of jobs after grasping which job uses which consumable.
Further, it is necessary to take into account influence of changing the order on other jobs than the job whose place in the order is intended to be changed, since a change in the place of one job in the order can cause another job to run out of a consumable, for example.
Particularly, in a case where the number of input jobs is larger, or in a case where the operator leaves the printing site for a long time period or a plurality of times, it is necessary to perform changing the execution order of jobs by trial and error until it is properly changed, which costs the operator much time and labor.